1. Field of the Invention
The invention relates to a gas switch provided with a body case wherein a switching unit is installed and an arc-extinguishing gas such as sulfur hexafluoride (SF.sub.6) or the like is enclosed at a constant pressure, and an actuating mechanism for operating the switching unit, and is particularly concerned with an apparatus for locking the actuating mechanism unoperatably when a pressure of the arc-extinguishing gas comes lower than a predetermined value and also for indicating a locked state resulting from the gas pressure drop.
2. Description of the Prior Art
Generally in this kind of gas switch, when a pressure of the arc-extinguishing gas comes lower than a predetermined value, a load switching capacity in the switching unit deteriorates to cause a fault according to circumstances. It is therefore necessary that the actuating mechanism be locked to avoid a danger due to an erroneous operation when the gas pressure drops. There is then proposed hitherto an apparatus wherein a lock member is disposed within an accommodating box installed on an outside of the body case, and the actuating mechanism is locked by the lock member at the time of gas pressure drop. However, according to such conventional apparatus, the lock member engages with a part of the actuating mechanism in the accommodating box, therefore the engaging state cannot be ensured externally. Accordingly, it is not definite whether a locked state of the actuating mechanism is caused by a gas pressure drop or other reason such as trouble on the mechanism or the like, thus leaving a problem that a working efficiency at the time of maintenance and check deteriorates.